How to use PHP arrays to implement verification code generation and verification functions

How to use PHP arrays to implement verification code generation and verification functions

Verification code (CAPTCHA) is a technology used to verify whether the user is a human rather than a machine. In operations such as website registration, login or form submission, verification codes can effectively prevent automated attacks by malicious programs. In this article, we will introduce how to use PHP arrays to generate and verify verification codes.

1. Generate verification code

We can first define an array containing all possible verification code characters, and then generate a random verification code of specified length as needed. The following is a sample code:

function generateCaptcha($length = 5) {
    $characters = array('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '2', '3', '4', '5', '6', '7', '8', '9');

    $captcha = '';
    $count = count($characters) - 1;

    for ($i = 0; $i < $length; $i++) {
        $index = rand(0, $count);
        $captcha .= $characters[$index];
    }

    return $captcha;
}

In the above code, we define a generateCaptcha function, which accepts an optional length parameter, which defaults to 5. The function first defines an array $characters containing all possible verification code characters, and then uses the rand function to generate a random index value to obtain a random character and append it to the verification code Code string $captcha. Finally, the generated verification code is returned.

2. Verify the verification code

After generating the verification code, we need to store it on the server side and verify it when the user submits the form. The following is a sample code:

function checkCaptcha($inputCaptcha, $storedCaptcha) {
    return strtolower($inputCaptcha) == strtolower($storedCaptcha);
}

In the above code, we define a checkCaptcha function, which accepts two parameters: the verification code entered by the user $inputCaptcha and Verification code $storedCaptcha stored on the server side. The function converts both verification codes into lowercase letters and compares them. If they are equal, it returns true, otherwise it returns false.

3. Usage Example

The following is a complete sample code that demonstrates how to generate a verification code, store the verification code and verify the verification code:

// 生成验证码
$captcha = generateCaptcha();

// 将验证码存储在会话中
session_start();
$_SESSION['captcha'] = $captcha;

// 假设用户提交的表单中包含一个名为input_captcha的输入字段
$inputCaptcha = $_POST['input_captcha'];

// 验证验证码
if (checkCaptcha($inputCaptcha, $_SESSION['captcha'])) {
    // 验证成功，执行相关操作
    echo "验证成功！";
} else {
    // 验证失败，显示错误提示
    echo "验证失败！";
}

In the above code , first call the generateCaptcha function to generate a verification code and store it in the session. After the user submits the form, we get the verification code entered by the user from the form and verify it using the checkCaptcha function. If the verification is successful, relevant operations are performed; if the verification fails, an error message is displayed.

Summary

Using PHP arrays can easily realize the verification code generation and verification functions. We can generate a random captcha by defining an array containing all possible captcha characters and ensure security by storing the captcha on the server side and validating it when the user submits the form. By using the above sample code, you can easily add verification code functionality to your website, improving security and preventing malicious attacks.

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